Radiant heat or Central air/heat?

[Bob Marino]

I have decided to finally get my garage/shop in some type of order. The winters and summers in NJ make an unheated/air conditioned shop very tough to work in.

It is an stand alone 2 car garage - that has currently has neither insulation nor heat/ac. I am renting a POD for storage of all the contents while I remedy the situation. The garage is about 17' x 25 and the construction (very old) is 2 x4's, which will be heavily reinforced. All tools will be on mobile bases, etc.

The question is whether to go with a radiant slab on top of the existing concrete and get a 10,000 BTU AC unit which will be window or wall mounted or a small ac/heat unit with some ducting - much like a small central ac/heating unit for the home? Prices are fairly comparable.

Bob

[Charlie Kocourek]

Hi Bob,

I live in Minnesota so I know weather extremes! My shop is in the basement of our house. We have radiant heat and we love it! Very even and comfortable. It is hard to keep a slab warm with forced air heating.

[Jim Becker]

If you have the means and the headroom, the radient heat would be the way to go, no question. IMHO, of course.

[Bob Marino]

If you have the means and the headroom, the radient heat would be the way to go, no question. IMHO, of course.

Jim,

Why's that?

Bob

[Jim Becker]

More even heat without stiring up dust...and no cleaning filters during the heating season. With the floor-based radient heat, you're heating the slab which in turn heats "you" and the space. The concrete also holds the heat, kinda like a battery, so it can also be quite efficient, even with a simple hot-water heater providing the heating action.

[Kurt Aebi]

Bob,

I think that Jim means that if you can raise the pad to make room for the tubing and not lose too much headroom.

I feel you should go with the Radiant and the 10K BTU unit. My father has radiant heat in the floor of his garage and I'd live there all winter, if I could! Nice form of heat - once the pad is warm, the room stays very comfortable w/o the temperature fluctuations the forced air would give you. I have redone my house with a hydronic system from Buderus and radiant heat-radiators, rather than tubing (since the house was made in the 1880's and has short (~7') ceilings and it really provides a nice even heat, even when it approaches -30°F here in Vermont.

If I build a new house or garage, Radiant will be my choice - without a doubt!!

[Larry Browning]

Radiant floor heat is by far the best solution. As JB and others have already pointed out you will be much happier with it than with any other solution. You should check out Radiant Floor Company (http://www.radiantcompany.com) They are geared to the DYI guy and will help you design your system and sell you all the supplies and equipment needed. They have several options for retro fitting an existing building. They helped me with mine.

[Jamie Buxton]

When you sell the home, won't the next owner find it easier to return the building to its garage purpose if you don't raise the floor?

[Ken Fitzgerald]

Bob radiant heat recovers quicker after you open and close the door in the winter. I'd have put radiant floor heat in my shop except that I don't have water or sewer in it and the lack of same caused some increased costs and the city balked at leaving a heating/ac permit open for extended period. The period would be extended as I'm doing it on a cash only basis.

[Jim Becker]

I think that Jim means that if you can raise the pad to make room for the tubing and not lose too much headroom.

Doh!! Yea...that's what I meant!! (And forgot to confirm)

[Michael Perata]

Bob

I agree with the suggestions to go radiant flooring. I would suggest you pop out the existing floor and add the heating pipes to a new concrete installation. The demo cost would probably be less than $1K.

By going new concrete you can bury your electrical and possibly your DC, and with the thicker imbedded slab, the heat loss would be less.

[Bob Reda]

Bob,


Another option is to use a co-ray-vac system, which is a radiant heat that runs above you(close to the ceiling) It is about 98% effiecent draws in air from the outside and vents out the outside. Very reasonable in cost also.

Bob

[Bob Marino]

Bob,


Another option is to use a co-ray-vac system, which is a radiant heat that runs above you(close to the ceiling) It is about 98% effiecent draws in air from the outside and vents out the outside. Very reasonable in cost also.

Bob

Bob,

Never heard of that one. Any links?

Bob

[Jim Becker]

Bob's suggestion is good if you have a high ceiling, but it's not very practical for an 8 footer...as to what it is, take a walk into Home Depot and look up. The system Bob is suggesting is similar to the radient tube system used in the stores. Radient is nice in that it heats "you" and "things" first and they in turn, will warm the air.

[Bob Reda]

They make the co ray ovac system for the home and it is not so intrusive. If placed right you will hardly notice it. As most local codes will state ductwork with registers are not permitted in garages ( fumes getting through the house let alone carbon monoxide)

[John Bush]

Hi Bob,
When I built my new shop I used radiant floor heating and have been very happy with the choice. I used a regular hot water tank(natural gas) and a manifold for distribution, a pump, thermostat and relay and the system has worked beautifully. I placed 2" rigid foam insulation under a vapor barrier, then 6" mesh and I tied the tubing to the mesh. I had concrete pros do the 4" slab. I looped the tubing on 12" centers with the maximun length of each zone @ 250'. The manifold I got has 4 zones with flow controls for each zone. I usually keep the temp ~ 65 deg. and if I leave the doors open for a while , the slab holds the heat well enough to warm the shop up quickly.
I think this would be the way to go for you shop space, but one thing to consider is how much heat loss would you get with no insulation. Some one had mentioned removing the old floor and reengineer a new one. That would be ideal, but I would want to know if the increased efficiency would pay for the additional cost. Good luck, John.

[Bob Marino]

John,

Yes, insulation is a key factor, no question. Though I have not yet decided I am leaning more in this direction.

Bob

[Frank Hagan]

People I've talked to "in the business" state that insulating the slab ... sides as well as underneath ... will save up to 25%. So if you leaning toward radiant floor heating, and wondering about the cost of demo and starting new, you can calculate the energy savings for a payback figure.

[Ken Fitzgerald]

Bob there are a number of manufacturers websites for DIYers where they not only help you design your system and sell you the parts, they'll show you the method of installation. Local heating companies here were even agreeable to me doing part of the installation (laying the tubing in floor and tying it to the 6x6 mesh). Insulation is the cheap, especially installing it during construction.

I investigated overhead radiant heat tubes......I didn't have the finished ceiling height to give the necessary "safety" room. I've noticed the last 2 years that I have less natural insulation (hair) than previous years and the heat on the head is more than just a nusance!

Good luck with your research and decision!

[Christopher Stahl]

Radiant heat is the best choice. As others have said, you'll save in energy because it's far more efficient. Forced air happens not to be very efficient at all and is a terrible way to heat.

I'm currently changing over to radiant floor heat in my house. I'm using a below floor installation where it is hung between the joists. You'll be able to do most of the work yourself. You'll probably be able to find someone local that can calculate the heat losses and design the layout of the tubing. Since you're heating the one area, you'll only need one zone which means less complication for the hookups.

If you want to save more money, you can look into a hot water assisted solar type heating. Very inexpensive and it's very efficient. Heats a tank of water before flowing into the water heater or boiler. This is part of my current setup.

chris

[Chris Fite]

In the shop that I am building, I installed radiant hydronic heat. I had read a lot about it for efficiency and effectiveness. The installation was straightforward: visquine, insulation, wire mesh, tubing, concrete. Although I did not pour the concrete, I installed the radiant system.

As with any other heated space, insulation is important. Using R-19 in the walls and R-49 in the attic, the 24x28 building with 12 foot ceilings has a heat load of 10,000 BTU. I will be tying it into the existing hot water system. Opposed the usual natural gas heat so popular here, the installed system was only $400 more than a gas unit would have been.

Of course, no one had done this in this area. It was an opportunity to learn: not only for me, but also for the concrete contractor.

It offers excellent heating as well as not have: filters, flame, and blowing air. The vendors were quite helpful.

[Bob Marino]

.
Thanks guys. What complicates the decision is the fact that it is a shop that will only see hobbyist useage, not hours a day, every day, not that that wouldn't be nice. :D I am trying to see if I can justify the expense for hobbyist type useage.
Do most folks maintain a stand alone shop at a certain temp in the winter, even if you don't use it for a week or so?

Bob

[Larry Browning]

Bob,
That was also a concern of mine. But I think if you set the thermostat at about 58-60 in the shop it will work out good for you. This will keep things like paint and glue from freezing yet allow you to work in comfort. Plus you will be surprised as to how little you will spend on heating cost. Of course if you won't be in the shop for weeks of months at a time you could turn down the tstat even lower. You may not have this problem in NJ, but here in AR we will have several days of warm weather in the winter which do not require heating at all, and even though the circulating pump will not kick on, the boiler(water heater) still cycles on an off anyway which a problem that forced air systems do not have.
You should really check out the different installation options that are available for radiant heating before deciding to jack hammer your floor and start over.

[Christopher Stahl]

With radiant floor heat, you won't adjust the thermostat like you do now. You set it and let it go. It can take 8-12 hours to heat the floor. So, you won't be adjusting it for times you're not there unless you're going to be gone for long periods of time, like a vacation.

Even for the usage you're talking about, it will still be worth the money. It's going to be fairly inexpensive to install and run. If you're bill changes by $5/month in the winter time, I would be surprised.

chris

[Bob Marino]

If I go radiant, I will go over the existing slab - it's in good shape and I don't think the loss of headroom will be an issue.

Bob

[Christopher Stahl]

One other thing, I probably wouldn't take a jackhammer to your floor. You can easily install this on top of your existing floor. You would gain very little by dropping in a new slab.

chris

[Paul Canaris]

Since the shop wont be a full time operation have you thought of using a heat pump (window mounted varieties are easy), it would provide both AC and heating, and is likely the least expensive solution..

[Keith Hooks]

Would it be possible to install radiant heating underneath a raised wooden floor? It seems like there are advantages to having a wooden floor and that wouldn't take up any more head room than another slab. But, perhaps a slab is required since concrete holds onto the heat better. Does anyone know?

[Christopher Stahl]

Keith,
You can install radiant hydronics under an existing floor. There is an advantage to a large slab, the amount of heat it can hold. You can install under a floor very easily. It will be slightly less efficient because of less mass to heat and the fact that the water will need to run at a higher temp through the flooring.

With under floor installation, you'll use aluminum heat transfer plates on the Pex tubing. Then the mass you heat will be a volume of air between the floor and a foil/bubble/bubble/foil insulation.

Not as good as a new installation, but far more efficient than forced air.

This is just some quick info. If you need more, feel free to contact me.

chris

[Jim Becker]

Would it be possible to install radiant heating underneath a raised wooden floor? It seems like there are advantages to having a wooden floor and that wouldn't take up any more head room than another slab. But, perhaps a slab is required since concrete holds onto the heat better. Does anyone know?

Yes, you can do this...the concrete is a better heat sink, but the wood floor would be more comfortable and also offer the opportunity to make it level without destroying the abilty to convert back to a garage in the future.